Electric switch



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J. D. WOOD ELECTRIC SWITCH Feb. 2, 1932.

Filed sept. 6,j 1928 fill Patented Feb. 2, 1932 UNITED STATES PATENT`OFFIICII?.

JOSEPH D. WOOD, OF WOLLASTON, MASSACHUSETTS ASSIGNOR TO CONDITELECTRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON,'MASSACHUSET-TS, ACORPORA- TION 0F MASSACHUSETTS ELECTRIC SWITCH Application filedSeptember 6, 1928. Serial No. 304,275.

This invention relates to electric switches and has particular referenceto high tension switches which interrupt their circuit under oil.

When an oil immersed switch opens to interrupt its circuit, aconsiderable volume of oil gases and vapors is given off due to thepresence of the circuit interrupting arc beneath the oil. These gasesand vapors are hot in their incipient state and the gases are frequentlyincandescent and highly conducting. It is desirable to retain thesegases land vapors within the casing as far as possible since by frequentoperation the level of the oil in the casing may be so diminished as torender the switch inoperative. It has-been found desirable, therefore,to retain these gases and vapors within the casing up to a certainelevated pressure consistent with safety, and to vent them from-thecasing when this safe pressure is exceeded. By this expedient some Vofthe oil gases and most of the vapors con dense upon cooling and are notlost from the casing, andwalso a partial vacuum is not formed in thecasing upon cooling of the products of circuit interruption with thesubsequent inlux of air and the resultant condition so conducive toexplosions. This arrangement, however, whereby the heated gases arepresent in the switch casing under an elevated pressure may create adangerous condition, for even small amounts of the heated gases escapingaround the switch operating rod, while not suiicient to nullify theabove stated purpose, may, due to their high conductivity, cause -aflash over by their presence in the vicinity of the exposed termi nals.The employment of a packed gland about the switch rod is undesirable,and in many cases it is necessary that the switch operating rod bepermitted ysome latitude of movement at the point where it passesthrough the casing. Furthermore any trictional restraint Whatever on theswitch op erating rod unnecessarily impedes the free and rapid openingmovement oit the switch member which is essential in a high voltageswitch.

It is therefore an object of this invention toprovide a irictionlessHuid sealing means between the switch casing and the movable switchoperating rod of an electric switch.

It is a further object toprovide aiiuid seal about a switch open rodyat'this point while permitting a loose runningfit between theA rod andcasing.

A further obj ect of the invention is the provision of a spring-urgedsealing member for the switch rod which also constitutes aA device toaccelerate the opening movement of the switch.

Another object of the invention is to provide improved acceleratingmeans for lthe movable switch member that acts thereon only during thefirst part or the switch opening movement.

A still further object is gener-ally'to improve the construction andperformance of oil immersed electric switches.

Fig. l is an elevation, partly in section, of an oil immersed electricswitch equipped with the Huid sealing means embodyingthe invention.

Fig. 2 is a detailed sectional elevation of the sealing means taken onlines 3-3 of Fig. 1.

F ig. 3 is a view similar to Fig. 2 with the parts in the switch openposition.

Fig. 4t is a section taken along lline 4-4 of Fig. 3. i

The single phase elec-tric switch herein shown includes a switch frame10 which comprises a support for the stationary and movable switchmembers and an oil receptacle 12 depending therebeneath. Said switchframe provides a fluid tight closure-for the open top of the said oilreceptacle 12, and means is provided to maintain said oil receptacleyieldingly in position against said switch frame. Said means includes ayoke 14 disposed beneath said oil receptacle and tie-bolts 16 which areextended throughvsaid yoke 14 and said switch frame 10. Springs 18 areprovided on said tie-bolts above said switch frame and nuts 20 serve tocompress springs 18 whereby to urge said receptacle 12 constantly intoengagement with a Vshoulder 19 of said switch frame 1-0. An outer opentop spill receptacle 22 is also secured dependingly to said switch frame10. Said -spill receptacle is supported with its open top in spacedrelation from said switch frame lO by means of brackets 24 which aresecured removably to said switch frame by means of bolts (not shown).The stationary switch members comprise a pair of spaced insulatingbushings 26 which extend through said switch frame 10 into and beneaththe oil in said receptacle 12. Stationary contact members 28' areprovided at the lower ends of said switch members beneath the oil insaid receptacle 12.

The movable switch member comprises an insulating rod 30 which carriesat its lower end a laminated brush member 32 which is adapted to engageand bridge the stationary contacts 28 in the usual manner. Saidinsulating brush rod 3() has at its upper end a metal switch operatingrod 34, somewhat smaller in diameter, which extends loosely through anaperture 39 in said switch frame 10, (Fig. 2). The upper end of saidoperating rod 34 is pivotally connected at 35 to suitable switchactuating mechanism 36 by which the movable switch member is actuatedbetween switch closed and switch open positions in the usual manner.

When the switch operates to interrupt its circuit oil gases and vaporsare generated which accumulate in the gas expansion space A above thelevel of the oil in the receptacle 12. A considerable proportion ofthese gases and vapors is condensible and for this reason the springs 18which support the inner oil receptacle aresufiiciently strong tomaintain the oil lreceptacle in its elevated position against the switchframe 10, whereby normally to prevent the ready escape of any materialquantity of these gases and vapors from the receptacle. When, however,an abnormal pressure occurs in the receptacle, the springs 18 areadapted to yield and permit the receptacle 12 to move downwardly awayAfrom the shoulder 19 of the switch frame 10 and thus to remove theclosure for the 'top of the receptacle 12 and reduce the pressuretherein to a safe value. A depending' flange or apron 37' is provided onsaid switch frame `into the vicinity of live switch terminals 38.

According to the invention, means is provided to seal the aperture 39 inthe switch frame 10 through which the switch operating rod 34 extends.Said means comprises, as shown particularly in Figs. 2 and 3, acylindrical housing 40 provided with a flange 42 which is adapted to besecured beneath the top of said switch frame 10, between the spaced ribs44 thereof. Said switch frame l0 is provided with an annular recess 46concentric with said aperture 39 therein and an annular flange 48 ofsaid housing 40 is adapted to be received therein, whereby to centersaid housing. Bolts 50 are passed loosely through said flange 42, andare screw threaded into said switch frame 10, and serve to support saidhousing removably in the aforesaid position on said switch falne. Saidhousing 40 is provided with a bottom closure 52 having an enlargedopening 53 therein through which said switch rod 34 is loosely extended.A sleeve 54 having an annular outstanding llange 5G at its upper end isprovided on said switch rod 34 with the flange 56 of .aid sleevedisposed within said cylindrical housing 40. Said sleeve extends looselythrough said passage 53 in the bottom 52 of the housing 40 in positionto engage the metal ferrule 57 on the upper end of rod 30 when thelatter is in an elevated position. The inner bore of said sleeve 54 isadapted to receive said operating rod 34 so as to provide a closerunning fit there-about, and adjacent faces 58 and 60 of said flange 5Gand said bottom closure 52 respectively are ground to provide a fluidtight seal about the opening 53 at the bottom of said cylinder 40 whenthey are in engagement. An accelerating spring G2 is disposed withinsaid housing 40 between the under face of said switch frame 10 and theupper end of said sleeve 54 above the flange 56 thereof, which spring isadapted to be compressed in the closed position of the switch, as shownin Fig. 2. A suitable bearing plate 64 is provided at the upper end ofsaid spring G2 which is arranged to have a close wiping contact at 65with the switch rod 34, and which is free for lateral movement in saidhousing 40.

lhen the switch is released for opening movement, the acceleratingspring 62 acts upon the switch rod 30 through the medium of said sleeve54 to give an initial impetus to the switch opening movement of themovable switch member. When the flange 56 of the sleeve 54 has moved asuflicient distance to engage the face 60 of the housing 40, as shown inFig. 3, the remaining tension of the spring 62 serves to maintain thecoolwratingr ground surfaces 58 and 60 firmly in engagement, whereby toprovide a fluid tight seal about the aperture 53 in the bottom of saidhousing 40. During the remainder of the switch opening movement thesleeve 54 remains in this position so that before an elevated pressureis developed in the receptacle due to the presence of the circuitinterrupting arc in the oil, the fluid tight seal is completed about theswitch rod 34, without imposing any restraint on the movable switchmember as is the case with the usual gland and packing construction. Theswitch rod 34 is free at all times for slight lateral movement in theaperture 39 of the switch frame and the aligned aperture 53 in thehousing 40, whereby slight inaccuracies in the switch actuatingmechanism will not cause the rod to bind. The relative strengths of thetank supporting springs 18 and the accelerating spring 62 are such thatthe pressure acting upwardly on the sleeve 54 will never be sulficientto raise the flange 56 off its seat 60 before the springs 18 will havepermitted the receptacle 12 to descend and relieve the pressure withinthe receptacle. Consequently, under no condition can oil escape aroundthe switch rod 34 into the vicinity of the switch terminals 38 but itYwill always be projected downwardly past the apron 37 into the outerspill receptacle 22.

The construction may be modified in many respects without departing fromthe scope of the invention.

I claim:

1. In an electric switch, the combination of an enclosing casing adaptedto contain cil, a switch operating rod extended through an aperture inone wall thereof, and means movable into and of sealing relation withsaid aperture having an operative connection with said switch operatingrod arranged to be moved into sealing relation with the aperture duringthe switch opening movement of said switch operating rod.

2. In an electric switch having an enclosing casing adapted to containoil and having stationary and movable contact members disposed thereinbeneath the oil, the combination of a switch operating ro'd extendedfreely through an aperture in a wall of said casing and connectedoperatively with said movable contacft member, an accelerating springdisposed about said rod, and sealing means for said aperture associatedwith said rod to compress said spring and uncover said aperture in theclosed position of the switch and to cover vsaid aperture in the openposition of the switch.

3. In an electric switch the combination of an enclosing casing adaptedto contain oil, a switch operating rod extended through an aperture in awall of said casing and axially movable therein between switch open andclosed positions, said rod being loosely received in the aperture insaid casing wall Ywhereby to permit a substantial lateral movementthereof in said casing, and accelerating means for said switch operatingrod, said accelerating means including a sleeve engageable with andhaving a close running fit on said rod inwsaid aperture and havingprovision for effecting a fluid tight seal of said aperture when vtheswitch is open.

l4. In an electric switch, the combination of an 'enclosing'casingadapted to contain oil and having an opening in a wall thereof above'the normal level of the oil, a housing secured in fluid tight relationto said casing over the opening therein, said housing having an openingtherein aligned with and spaced from the opening in said casing, aswitch operating rod having a .reduced upper metal portion looselyreceived in the aligned openings in said casing and housing and a lowerenlarged insulating portion disposed beneath said housing extended intothe oil in said casing, and means carried by the upper portion of saidrod and loosely disposed in said housing and extended through theopening therein to engage the lower insulating portion of said rodarranged to cooperate with said housing` to provide a fiuid tight sealbetween said rod and housing in the vicinity of the opening therein.

5. In an electric switch, the combination of an enclosing casing adaptedto contain oil, and having an aperture in a wall thereof above the levelof the oil, a housing secured in fluid tight relation to said wall aboutsaid aperture and above the oil in the casing, said housing having anaperture spaced from and aligned with the aperture in said casing wall,a switch operating rod extended into said, casing through said housingand received loosely in said aligned apertures, an accelerating sprincarried by said rod and disposed within said housing between said spacedapertures, and a sleeve carried loosely by said rod arranged to compresssaid spring when said rod is moved to switch closed position, saidsleeve being biased by said spring in the switch open position of saidoperating rod into position to seal the passage through said housing atthe aperture therein.

6. In an electric switch, the combination of an enclosing casing adaptedto contain oil and having a gas expansion space above the oil, saidcasing having an aperture in a wall thereof in communication with saidgas expansion space, an open-top housing disposed within said casinghaving 'its open top secured in fluid tight relation to and surroundingthe aperture in said casing wall, said housing having an aperture in itsbottom wall ali gned with the aperture in said casing wall, a switchoperating rod extended loosely through the aligned apertures in saidcasing and housing, a sleeve closely surrounding and slidable on saidoperating rod and extended loosely through the aperture in said housing,said sleeve having an outstanding flange disposed within said housingand arranged t-o engage the lower wall of said housing to provide afluid tight seal about rthe aperture therein, and resilient meansdisposed within said housing to bias said sleeve into sealing engagementwith said housing.

7. In an electric switch, the combination of an enclosing casing adaptedto contain oil and having a gas expansion space above the oil, saidcasing having an aperture in a wall thereof in communication with saidgas expension space, an open-top housing disposed within said casinghaving its open to-p secured in fluid tight relation to and surroundingthe aperture in said casing wall, said housing having an aperture in itsbottom wall aligned with the aperture in said casing wall, a switchoperating rod extended loosely through the aligned apertures in saidcasing and housing, a sleeve closely surrounding and slidable on saidoperating rod and extended loosely through an aperture in said housing,said sleeve having an outstanding flange disposed within said housingand arranged to engage the lower wall of said housing to provide a fluidtight seal about the aperture therein, and resilient means disposedwithin said housing to bias said sleeve into sealing engagement withsaid housing, and an abutment on said rod arranged to engage and movesaid sleeve upwardly on said rod against the bias of said spring in theswitch closed position of said switch operating rod.

8. In an electric switch, the combination of an oil-containing enclosingcasing, contacts separable Within said casing, an operating rod for saidcontacts extended into said casing through an opening therein, a valvemember for closing said opening having means engaged by said rod formoving it away from said opening, and other means operable when saidvalve member is disengaged from. said rod for moving said valve membertoward said opening.

9. In an electric switch, the combination of an oil-containing casing,separable contacts enclosed therein, operating mechanism for saidcontacts including an operating rod movable in the direction of itslength through an aperture in said casing, a long sleeve slidable onsaid rod having an enlarged head which can seat on said casing over saidaperture to seal it, said rod having a step which engages said sleeve tomove it away from said aperture when said rod is moved in one direction,and a spring bearing on said sleeve to move it in the opposite directioninto sealing relation with said aperture, said spring also actingthrough said sleeve to move said rod.

10. In an electric switch, the combination ot a casing having a wallprovided with a rod-opening, a housing secured to said wall about saidopening and having an opening in one end aligned with said wall openinga switch rod passed through said wall opening and housing, a valvemember slidable on said rod, and a spring located in said housing urgingsaid valve member against said housing-opening, said rod having means tomove said valve member away from said opening.

11. In an electric switch, a wall having an opening, a housing securedto said wall about said opening and having an opening in the v endthereof aligned with said wall opening,

a. switch operating rod extended through said openings, a sleeveslidable on said rod in said housing-opening having an outstandingflange in said housing which overlies said housing-opening, a spring forholding said flange on said housing over its opening, and an abutment onsaid rod which engages said sleeve and moves said Hange away from saidhousing-opening.

l2. ln an electric switch, stationary and movable switch members, saidmovable switch member having a lifting rod, means providing a pair otfixed abutments which are disposed adjacent and are spaced axially ofsaid rod, a spring located between said abutments and bearing againstone of them, a sleeve axially loose on said rod against which saidspring bears and having an outstanding part which overlies said otherabutment and is held thereagainst by said spring, said rod having anabutment which is engageable with and can move said sleeve toward saidother abutment, said rod being irce for a predetern'iined extent ofmovement independent of said sleeve.

'13. ln an electric switch, a wall having achamber with aligned openingsat the outer and inner ends thereof, a switch operating rod extendedthrough sid openings, a helical compression spring located within saidchamber surroundingl said rod and normally held in a partially stressedcondition by the ends of said chamber, and means operative in responseto switch closing movement of said rod for further compressing saidspring.

1.4. In an electric switch, an enclosing casing having an opening in a`wall thereo'l, a housing secured to said casing having opein ings in itsopposite end walls which are aligned with said casing opening, a switchoperating rod extended through the aligned openings of said casing andhousing, a compression spring surrounding said rod in said housing whichis held in a partially stressed condition, between said casing andhousing walls, and means operative in response to switch closingmovement of said rod for further compressing said spring.

l5. In an electric switch, an enclosing casing having an opening in awall thereof, a housing secured to said casing having openings in itsopposite end walls which are aligned with said easing opening, a switchoperating rod extended through the aligned openings of said casing andhousing, a compression spring surroundinir said rod in said housingwhichis held in a partially stressed condition between said casing andhousing walls, and means operative in response to switch closingmovement of said rod for further compressing said spring, said meansincluding an operating member carried by and having a lost motionconnection with said rod, and an abutment on said rod arranged to engagesaid operating member only in the final switch closing movement of saidrod.

16. In an electric switch, a wall having an opening, a housing securedto said wall about said opening having an opening in the end thereofwhich is aligned with said wall opening, a switch operating rod extendedthrough said openings, a sleeve slidable on said rod in saidhousing-opening having an outstanding flange located in said housingwhich overlies said housing-opening, a stressed spring located in saidhousing for holding said iange on said housing over its opening, switchoperating mechanism for reciprocating said rod between a switch open anda switch closed position, and means to further compress said spring uponmovement of the rod to -switch closed position including an abutment onsaid rod which engages and actuates said sleeve in the final switchclosing movement of said rod.

17. In an electric switch, a casing wall having an opening, a housingsecured to said wall about said opening having an opening` in the endthereof which is aligned with said wall opening, a switch operating rodextended loosely through said openings having an enlarged lower portionand a reduced upper portion which is located within said housing, asleeve slidably carried by the upper portion of said rod and extendedloosely through and having its lower end terminate beyond the opening insaid housing, said sleeve having an outstanding flange at its other endwhich is within said housing and which overlies said housing-opening, ahelical spring located in said housing surrounding said rod and holdingsaid flange against said housing over its opening, switch operatingmechanism for reciprocating said switch operating rod between a switchclosed position in which the lower end of said sleeve is engaged by andis moved upwardly against the action of sv id spring by the enlargedlower portion of said rod, and a switch open position in which saidflange is held over said housing opening by said spring and the enlargedlower portion of said rod is moved out of engagement with and below thelower end of said sleeve.

18. In an electric switch, the combination of a horizontal casing wallhaving an opening, a vertically disposed switch operating rod having alower enlarged portion and an upper reduced portion which is extended insaid casing opening, a helical compression spring encircling the reducedportion of said rod beneath said casing wall, a sleeve slidable on thereduced upper portion of said rod between said spring and the enlargedportion of said rod, said sleeve adapted to compress said spring uponupward movement of the rod into switch closed position, and means toarrest the downward movement of said sleeve upon downward movement ofsaid operating rod at a point at which said spring is still in acondition of stress.

19. In an electric switch, the combination of a casing wall having anopening, a switch operating rod extended through said opening and havingan abutment thereon which is spaced from said casing wall, a helicalcompression spring surrounding said rod between said wall and abutment,said abutment ar- 'anged in the switch closed position of said rod tocompress said spring whereby to store up energy for a subsequent openingmovement of the rod, and means including a housing disposed about saidspring for limiting the recoil of said spring upon switch openingmovement of said rod.

20. In an electric switch, the combination yof a casing wall having anopening, a switch operating rod having a lower enlarged portion and anupper reduced portion which is extended in said casing opening, ahelical compression spring encircling the reduced portion of said switchoperating rod which in the switch closed position of said rod iscompressed between the enlarged portion of said rod and said casingwall, the enlarged portion of said rod being free from engagement withsaid spring in the switch open position thereof, and means including acasing surrounding said spring to restrict the recoil thereof uponopening the switch whereby to maintain said spring always under stressirrespective of the position of said rod.

In testimony whereof, I have signed my name to this specification.

JOSEPH D. WOOD.

